With one quick additional 3D-printed part, the vinyl cutter becomes a pen plotter!

Look for the 'Bic holder' STL in the files section. Simply remove the barrel from a cheap Bic ballpoint and stuff it in the hole. If the hole's too tight, open it out with a 4.0mm drill.

As before, use Gcodeplot for Inkscape to convert paths to GCode toolpaths and you're away...